Color Computer 2

Color computer 2

More model specific info and pics can be found here:

Color Computer 2

Models

The CoCo2 was first released in September of 1983.

26-3026 model (16K Color Basic ) - September 1983

The first CoCo 2 model released included 16K RAM with standard Color BASIC and was listed in Radio Shack catalogs at U$239.95. The case was a bit smaller than the original CoCo, very similar to the TDP-100. The keyboard was much better than the original CoCo "chicklet" keyboard. They were lower profile than typical modern PC keyboards and the keys were recessed in the center, giving them a "melted" look - a term now used to described this model.

The circuit boards were revised to be a bit smaller than previous models and were equipped to run a full 64K. Most of its chips are socketed. This machine is based on the #8709416 PC board, and has a large, upright RF modulator with integrated TV channel 3/4 switch.

Also characteristic of this machine is the use of a large power supply pass transistor (in a TO-3 package). The two 24-pin ROM sockets are located near the cartridge/system bus connector, and the eight RAM chips are located in a single row under the keyboard.

(Note that this same model number has reportedly been found on larger, Korean-made CoCo models in Australia.)

26-3027 (16K Extended Color Basic), 26-3003 (64K Extended Color BASIC)

This 16K ECB model was listed for $319.95, $399.95 for 64K. A 64K RAM upgrade (26-3017) was "only" $149, and the Extended BASIC ROM upgrade was $79.95, making the $399.95 26-3003 a relative bargain (add the ROM and RAM upgrade to a 16K basic model the total price was $468.90).

This machine is identical to the 26-3026, with the exception that it already has the Extended BASIC ROM factory-installed.

Upgrades

• RAM : To upgrade the 26-3026 or 26-3027 to 64 KB of RAM, it is necessary to replace the eight 8040517 chips with 4164 chips of 200 ns or better access time, and to solder a wire between the two pads labeled W1. W1 is located between U6 and U7.

26-3127 (64K, Extended Color Basic)

This is the first '64K Color Computer 2'. It also featured the 'enhanced' keyboard, otherwise, it is identical to the 26-3026/26-3027.

Upgrades

• RAM : RAM : Note that the RAM is soldered in place in those machines which were factory-equipped with 64K, making replacement thereof a bit more difficult if necessary. For this reason, the 26-3026 and 26-3027 variants are favorites among CoCo 2 enthusiasts.

Pricing

Prices dropped quickly. In mid 1984 RS cut the price for the 16K standard model to $159.95 and the 16K Extended BASIC model to $199.95. Production then shifted from Tandy's US plant to a Korean subcontractor. Those models appeared in mid 1984 at the same prices as the previous models, with new model numbers and revised circuit boards. For Christmas 1984 prices were reduced -- $99.95 for a standard Color BASIC 16K model (31-3134), $139.95 for 16K and Extended Color BASIC (31-3136), and $199.95 with 64K and Extended Color BASIC (31-3127). Prices continued to drop as the home computer market got very competitive and IBM PC clones started coming down in price.

To put these prices in perspective, the new for 1985 Tandy 1000, which was an IBM PC clone (actually an enhanced IBM PC Jr. clone that could be upgraded to standard IBM PC specs) was listed at $1199 with 128K RAM and a single 360K floppy drive. An RF modulator could be purchased ($24.95) to use a standard TV as a display (limited to 40 columns) or a digital $159.95 monochrome/$549.95 color monitor could be used. The CoCo 2 was a relative bargain, although there were a few IBM clones that could be purchased a bit cheaper than the Tandy 1000. In 1987 the Tandy 1000SX was priced at $849 with 384K of RAM and one 360K floppy drive.

The final CoCo2 was listed in the 1987 Tandy catalog for only $99.95 with 64K and Extended Color BASIC.

Differences

Extracted from The CoCo 2, introduced in 1983, is basically a refinement of Radio Shack's original TRS-80 Color Computer. It utilizes a more efficient power supply, higher integration (lower parts count), and a smaller case. The primary goal of these modifications was most likely to lower its manufacturing cost. The only significant functional difference between the two is the absence in the CoCo 2 of a regulated +12VDC power supply. One of the few devices which actually requires this power source is the first-generation floppy disk controller sold for the original CoCo. All subsequent controllers operate exclusively from the +5VDC line. The CoCo 2 was initially offered with 16 kilobytes of RAM, with the option of upgrading it to 64 kilobytes. Doing so requires considerably less effort than in previous models (typically replacing the RAM chips and soldering one jumper).

While the original CoCo used a keyboard with small, flat, square keys (usually referred to as the 'chicklet' keyboard) and a gray-colored case, the CoCo 2 brought with it a more 'modern' off-white case and a keyboard with 'sculptured' keys. Some describe these early CoCo 2 keyboards as having keys which appear to be 'melted'. The travel distance of said keys is fairly low, as with the chicklet keyboard.

Detailed models and upgrades

CAUTION! DO NOT ATTEMPT TO UPGRADE ANY CoCo RAM OR ROM WITHOUT FIRST SECURING SPECIFIC UPGRADE INSTRUCTIONS FOR YOUR MACHINE!

Please note that improper upgrade attempts have been known to destroy the majority of the chips in a CoCo! Note also that the RAM chips used in the 16K CoCo 2 are not the 4116s which one might have expected. The 4116 requires additional power supply voltages not supplied by the CoCo 2. Therefore, a special 16K by 1 bit RAM chip requiring only +5VDC is used. This chip has the Tandy house number 8040517. The RAM used in most 64K CoCo 2s consists of standard 4164 chips. CoCo 2 RAM upgrade information may be found below in the sections specific to each 16K CoCo 2 version.

Like the original Color Computer, the CoCo 2 has provisions for two ROMs: Color BASIC and Extended BASIC. Each consists (in most cases) of 8 kilobytes of data in a 24-pin ROM chip. The Color BASIC ROM is present in every CoCo. It contains the minimal BASIC interpreter and necessary routines to drive the machine's keyboard, video circuitry, and I/O ports. The optional Extended BASIC ROM adds extra graphics commands and other assorted functionality enhancements. Extended Color BASIC (the composite of both ROMs) is also required in order to utilize a floppy disk controller on a CoCo. Those machines which shipped without the Extended BASIC ROM could be upgraded (in most cases) simply by plugging the expansion ROM into the appropriate empty socket. The remaining machines shipped with the ROM already in place. Note that most CoCo 2s use version 1.2 of the Color BASIC ROM, and all Extended CoCo 2s use version 1.1 of Extended BASIC (the two ROM versions are independent). A Color BASIC machine displays its Color BASIC version at powerup; an Extended Color BASIC machine displays its Extended BASIC version. The BASIC command 'EXEC 41175' will display the Color BASIC ROM version in an Extended Color BASIC machine.

Before long, Radio Shack began to offer an additional model of the CoCo 2: one with Extended Color BASIC and 64 kilobytes of RAM already installed. This machine also shipped with a newly-designed keyboard, with greater key travel than either of the previous styles. Before long, every new CoCo 2 began to ship with this new, 'enhanced' keyboard. Note that late-model CoCo 1 chicklet keyboards, all CoCo 2 keyboards, and even CoCo 3 keyboards use the same type of mylar ribbon cables and are interchangeable. The CoCo 3 keyboard (and some third-party designs) utilize previously-unused positions in the CoCo's keyboard matrix, adding several new keys. Appropriate software can make use of the extra keys on any CoCo model. Note that the style (appearance, key travel, etc.) of the CoCo 3 keyboard is identical to that of the later CoCo 2 keyboard, with the exception of its extra keys.

Radio Shack switched, during the production of the CoCo 2, from the use of the 'TRS-80' label to the 'Tandy' label on its computer products. For this reason, the CoCo 2 can be found with either label. The vast majority of samples seen and possessed by the author display the TRS-80 label. The Tandy label appears to coincide accurately with yet another variation among CoCo 2 models: the presence of the enhanced MC6847T1 VDG (Video Display Generator) chip therein. Every original CoCo and the majority of CoCo 2s (those displaying the TRS-80 label) use the earlier MC6847. As its name implies, the VDG generates the CoCo's video output. The plain 6847 version contains only uppercase characters in its internal character set, whereas the 6847T1 also contains lowercase characters. Note that software and hardware solutions have been created to overcome this limitation of the 6847, without which lowercase characters are displayed as reverse-video uppercase characters. Conversely, while the 6847T1 is capable of generating true hardware-based lowercase, that capability is seldom exploited.

NOTE: Information is still being compiled and confirmed about the various models, particularly those in the A- and B-series. Updates will likely be forthcoming......